This draft proposal for async generators in ECMAScript 7 may be interesting reading to those who haven’t already: https://github.com/jhusain/asyncgenerator <https://github.com/jhusain/asyncgenerator>
This talk also has some good ideas about them, though the interesting stuff about using async generator syntax is all on the last slide, and not really explained: https://www.youtube.com/watch?v=gawmdhCNy-A <https://www.youtube.com/watch?v=gawmdhCNy-A> > On May 5, 2015, at 3:55 PM, Guido van Rossum <gu...@python.org> wrote: > > One small clarification: > > On Tue, May 5, 2015 at 12:40 PM, Jim J. Jewett <jimjjew...@gmail.com > <mailto:jimjjew...@gmail.com>> wrote: > [...] but I don't understand how this limitation works with things like a > per-line file iterator that might need to wait for the file to > be initially opened. > > Note that PEP 492 makes it syntactically impossible to use a coroutine > function to implement an iterator using yield; this is because the generator > machinery is needed to implement the coroutine machinery. However, the PEP > allows the creation of asynchronous iterators using classes that implement > __aiter__ and __anext__. Any blocking you need to do can happen in either of > those. You just use `async for` to iterate over such an "asynchronous stream". > > (There's an issue with actually implementing an asynchronous stream mapped to > a disk file, because I/O multiplexing primitives like select() don't actually > support waiting for disk files -- but this is an unrelated problem, and > asynchronous streams are useful to handle I/O to/from network connections, > subprocesses (pipes) or local RPC connections. Checkout the streams > <https://docs.python.org/3/library/asyncio-stream.html> and subprocess > <https://docs.python.org/3/library/asyncio-subprocess.html> submodules of the > asyncio package. These streams would be great candidates for adding > __aiter__/__anext__ to support async for-loops, so the idiom for iterating > over them can once again closely resemble the idiom for iterating over > regular (synchronous) streams using for-loops.) > > -- > --Guido van Rossum (python.org/~guido <http://python.org/~guido>) > _______________________________________________ > Python-Dev mailing list > Python-Dev@python.org > https://mail.python.org/mailman/listinfo/python-dev > Unsubscribe: > https://mail.python.org/mailman/options/python-dev/ryan%40ryanhiebert.com
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